Thanks for posting CCL
it just sounds like there has been a bit of a mix up and some confusion here. Hopefully everything is a bit clearer now?
The ponies were sold as bait, so I think thats the kind of thing people normally expect on bait ponies . if you are worried about the cancer possibly spreading, then give the cancerous ponies an oxyclean bath - that will not remove the marks, but it will kill off any mold etc